ATEX Control System Case Study

One of our primary customers came to us to discuss a requirement they had for a Hazardous area, road tanker top loading system which had been ordered from them. The system was being used to load a liquid product that was both flammable and hazardous to handle.

Using their expertise in their field they were able to supply a mechanical system which suited the arduous duty. However, additional safety requirements demanded an automated control system to ensure that the automatic valves incorporate a “self checking” feature, control the amount of product delivered and incorporate the required safety features, earth interlocking, overfill prevention and manually initiated emergency stop.

This is just the sort of project which we relish, so, we began.

Initially, we needed to communicate the overall design philosophy to our customer and the end client, in an easy to understand graphical manner, our thought process and how the various features would interact with each other. To that end we produced an initial block diagram (below).

From the discussions which this document enabled, we were able to move onto a design for the control panel (excerpts below).

Next, after careful selection of components, we were able to move onto the physical design of the enclosure and the layout of components.

Once all of the above stages had been approved, we moved onto the actual manufacturing, software development and testing of the control panel.

As the control system also incorporated intrinsically safe circuits, with the associated transformer isolated barriers installed into our control panel, we were additionally tasked with conducting the IS calculations.

After the panel was shipped to the Italian manufacturer of the loading equipment, we attended their factory to assist the final factory commissioning and customer factory acceptance test. The manufacturer produced the following video of the system.